We have received news from Let’s Encrypt that due to a security issue they will be revoking a significant number of certificates. You can read the announcement here: https://community.letsencrypt.org/t/revoking-certain-certificates-on-march-4/114864
As soon as our team received this information, we have been working to replace as many certificates as we possibly can prior to them being revoked. Some certificate regenerations are failing due to domain expirations or DNS no longer pointing to Kinsta.
Our engineers can and will go through each alerting site one-by-one and will fix these issues manually but that will take a significant amount of time. If you experience issues with your site's Let's Encrypt SSL certificate being revoked, please let our support team know. We have set up internal procedures to give priority to these issues and we will work towards solving each issue as fast as humanly possible.